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        <title>OpenLayers Paging Strategy Example</title>
        <link rel="stylesheet" href="../theme/default/style.css" type="text/css">
        <link rel="stylesheet" href="style.css" type="text/css">
        <script src="../lib/OpenLayers.js"></script>
        <script type="text/javascript">
            var map, photos, paging;

            /**
             * A specific format for parsing Flickr API JSON responses.
             */
            OpenLayers.Format.Flickr = OpenLayers.Class(OpenLayers.Format, {
                read: function(obj) {
                    if(obj.stat === 'fail') {
                        throw new Error(
                            ['Flickr failure response (',
                             obj.code,
                             '): ',
                             obj.message].join(''));
                    }
                    if(!obj || !obj.photos ||
                       !OpenLayers.Util.isArray(obj.photos.photo)) {
                        throw new Error(
                            'Unexpected Flickr response');
                    }
                    var photos = obj.photos.photo, photo,
                        x, y, point,
                        feature, features = [];
                    for(var i=0,l=photos.length; i<l; i++) {
                        photo = photos[i];
                        x = photo.longitude;
                        y = photo.latitude;
                        point = new OpenLayers.Geometry.Point(x, y);
                        feature = new OpenLayers.Feature.Vector(point, {
                            title: photo.title,
                            img_url: photo.url_s
                        });
                        features.push(feature);
                    }
                    return features;
                }
            });
        
            function init() {
                map = new OpenLayers.Map('map');
                var base = new OpenLayers.Layer.OSM();

                var style = new OpenLayers.Style({
                    externalGraphic: "${img_url}",
                    pointRadius: 30
                });

                paging = new OpenLayers.Strategy.Paging();

                photos = new OpenLayers.Layer.Vector("Photos", {
                    projection: "EPSG:4326",
                    strategies: [new OpenLayers.Strategy.Fixed(), paging],
                    protocol: new OpenLayers.Protocol.Script({
                        url: "http://api.flickr.com/services/rest",
                        params: {
                            api_key: 'b5e8c0e287e678671c3d8b2c0f3ced85',
                            format: 'json',
                            method: 'flickr.photos.search',
                            extras: 'geo,url_s',
                            per_page: 100,
                            page: 1,
                            bbox: [-180, -90, 180, 90]
                        },
                        callbackKey: 'jsoncallback',
                        format: new OpenLayers.Format.Flickr()
                    }),
                    styleMap: new OpenLayers.StyleMap(style)
                });

                map.addLayers([base, photos]);
                photos.events.on({"featuresadded": updateButtons});
                map.setCenter(new OpenLayers.LonLat(0, 0), 1);
            }
            
            function updateButtons() {
                document.getElementById("prev").disabled = (paging.pageNum() < 1);
                document.getElementById("next").disabled = (paging.pageNum() >= paging.pageCount() - 1);
                document.getElementById("num").innerHTML = paging.pageNum() + 1;
                document.getElementById("count").innerHTML = paging.pageCount();
            }
        </script>
    </head>
    <body onload="init()">
        <h1 id="title">Paging Strategy Example</h1>
        <div id="tags">
            vector, feature, stylemap, paging, strategy, flickr, script
        </div>        
        <p id="shortdesc">
            Uses a paging strategy to cache large batches of features and render a page at a time.
        </p>
        <div id="map" class="smallmap"></div>
        Displaying page <span id="num">0</span> of <span id="count">...</span>
        <button id="prev" disabled="disabled" onclick="paging.pagePrevious();">previous</button>
        <button id="next" disabled="disabled" onclick="paging.pageNext();">next</button>
        <br><br>
        <div id="docs">
            <p>The Paging strategy lets you apply client side paging for protocols
            that do not support paging on the server.  In this case, the protocol requests a
            batch of 100 features, the strategy caches those and supplies a single
            page at a time to the layer.</p>
            <p>This particular example uses the <a
                href="http://www.flickr.com/services/api/">Flickr API.</a></p>
        </div>
    </body>
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